Letexier Dominique, Pinteur Claudie, Large Valérie, Fréring Vincent, Beylot Michel
INSERM U 499, Faculté RTH Laennec, 69008 Lyon, France.
J Lipid Res. 2003 Nov;44(11):2127-34. doi: 10.1194/jlr.M300235-JLR200. Epub 2003 Aug 1.
Lipogenesis is considered less active in human than in rat adipose tissue. This could be explained by different nutritional conditions, namely high-carbohydrate (HCHO) diet in rats and high-fat (HF) diet in humans. Adipose tissue was sampled (postabsorptive state) in rats and humans receiving HCHO or HF diets, ad libitum fed humans, and obese subjects. We measured 1) mRNA concentrations of fatty acid synthase (FAS), acetyl-CoA carboxylase 1 (ACC1), sterol regulatory element binding protein 1c (SREBP-1c), and carbohydrate response element binding protein (ChREBP), 2) SREBP-1c protein, and 3) FAS activity. FAS, ACC1, ChREBP, and SREBP1-c mRNA concentrations were unaffected by diet in humans or in rats. FAS and ACC1 mRNA levels were lower in humans than in rats (P < 0.05). FAS activity was unaffected by diet and was lower in humans (P < 0.05). SREBP-1c mRNA concentrations were similar in rats and humans, but the precursor and mature forms of SREBP-1c protein were less abundant in humans (P < 0.05). ChREBP mRNA concentrations were lower in humans than in rats. In conclusion, the lipogenic capacity of adipose tissue is lower in humans than in rats. This is not related to differences in diet and is probably explained by lower abundance of SREBP-1c protein. A decreased expression of ChREBP could also play a role.
脂肪生成在人体中的活性被认为低于大鼠脂肪组织。这可能是由不同的营养状况所解释的，即大鼠的高碳水化合物（HCHO）饮食和人类的高脂肪（HF）饮食。在接受HCHO或HF饮食的大鼠和人类、随意进食的人类以及肥胖受试者中（处于吸收后状态）采集脂肪组织样本。我们测量了：1）脂肪酸合酶（FAS）、乙酰辅酶A羧化酶1（ACC1）、固醇调节元件结合蛋白1c（SREBP-1c）和碳水化合物反应元件结合蛋白（ChREBP）的mRNA浓度；2）SREBP-1c蛋白；以及3）FAS活性。FAS、ACC1、ChREBP和SREBP1-c的mRNA浓度在人类或大鼠中不受饮食影响。FAS和ACC1的mRNA水平在人类中低于大鼠（P<0.05）。FAS活性不受饮食影响，且在人类中较低（P<0.05）。SREBP-1c的mRNA浓度在大鼠和人类中相似，但SREBP-1c蛋白的前体和成熟形式在人类中含量较低（P<0.05）。ChREBP的mRNA浓度在人类中低于大鼠。总之，人体脂肪组织的脂肪生成能力低于大鼠。这与饮食差异无关，可能是由于SREBP-1c蛋白含量较低所致。ChREBP表达的降低也可能起作用。
